When the conductors in a flat cable must be removably connected to conductors on a circuit board, it is common practice to use multi-contact electrical connectors of the type comprising an insulating housing having a cable-receiving face and a rearward face, upper and lower sidewalls and endwalls extending between the faces, a cable-receiving trough extending into the housing from the cable-receiving face, and a plurality of contact terminals mounted in the trough, the terminals being arranged in a row extending between the endwalls so that the side-by-side conductors in the flat cable are contacted by the terminals when the cable is inserted into the trough. U.S. Pat. No. 3,989,336, U.S. Pat. No. 3,629,787 and U.S. Application Ser. No. 214,859, filed Dec. 10, 1980, all disclose such connectors.
An essential performance requirement of these connectors is that the flat cable not be damaged during insertion into the connector by an excessive resistive force produced by the contact terminals. Providing a connector with low insertion force, however, undesirably reduces the cable retention capacity of the connector, thereby permitting the cable to be disengaged from the connector upon application of a relatively small tensile pull on the cable. This may be unsafe under certain operating conditions.
One solution has been to incorporate strain relief means into the connector. The connector shown in U.S. Pat. No. 3,989,336 has strain relief ears on a flap which is hinged to the connector housing. These ears extend into cable openings to secure the cable in the connector housing. While this type of strain relief is undoubtedly effective, it is relatively complex and would be expensive to manufacture. Also, because strain relief is not required in all applications, fabrication of two types of connectors, one with and one without strain relief, would be necessitated. In addition, when a connector without strain relief is chosen for a particular application, but it is later discovered that strain relief is required, the entire connector must be removed and a new one installed having the strain relief feature. The present invention is directed to the achievement of a strain relief and connector for flat cable in which the strain relief is separable from the connector housing.
A strain relief and connector in accordance with the invention comprises a rigid body portion which is disposed against the upper sidewall of the connector housing. The body portion has ends which are adjacent to the housing endwalls and a forward edge adjacent to the cable-receiving face. Disposed against the endwalls are latching arms that have latching portions which are in engagement with latching shoulders on the endwalls. Flexible neck portions connect the latching arms to the ends of the body portion and permit outward movement of the latching portions from the endwalls so that the latching portions can be disengaged from the latching shoulders. At least two cable-retaining ears extend laterally from the forward edge of the body portion to free end portions which are received in openings in the cable.
U.S. Pat. No. 4,172,626 discloses a strain relief that is separable from a connector for flat cable. The connector is a connector clip having a row of cantilever springs resiliently biased against the circuit board connectors. A strain relief halter used with this connector clip as disclosed, however, is not adaptable to a connector of the type comprising an insulating housing having a plurality of terminals mounted therein.
A further advantageous feature of the present invention not available in any prior art connector having a strain relief is an overload release mechanism. Upon application of a tensile pull on the cable of a prior art connector, the strain relief retained the cable in the connector until the cable, the connector, and/or the strain relief were damaged. The present invention provides a mechanism whereby the strain relief disengages from the connector housing upon application of a predetermined tensile pull so that such damage is prevented.